As worldwide petroleum deposits decrease, there is rising concern over shortages and the costs that are associated with the production of hydrocarbon products. As a result, alternatives to products that are currently processed from petroleum are being investigated. In this effort, biofuels such as biodiesel have been identified as a possible alternative to petroleum-based transportation fuels. In general, biodiesel is a fuel comprised of mono-alkyl esters of long chain fatty acids derived from plant oils or animal fats. In industrial practice, biodiesel is created when plant oils or animal fats are reacted with an alcohol, such as methanol.
For plant-derived biofuel, solar energy is first transformed into chemical energy through photosynthesis. The chemical energy is then refined into a usable fuel. Currently, the process involved in creating biofuel from plant oils is expensive relative to the process of extracting and refining petroleum. It is possible, however, that the cost of processing a plant-derived biofuel could be reduced by maximizing the rate of growth of the plant source. Because algae is known to be one of the most efficient plants for converting solar energy into cell growth, it is of particular interest as a biofuel source. However, current algae processing methods have failed to result in a cost effective algae-derived biofuel.
In overview, the biochemical process of photosynthesis provides algae with the ability to convert solar energy into chemical energy. During cell growth, this chemical energy is used to drive synthetic reactions, such as the formation of sugars or the fixation of nitrogen into amino acids for protein synthesis. Excess chemical energy is stored in the form of fats and oils as triglycerides. Thus, the creation of oil in algae only requires sunlight, carbon dioxide and the nutrients necessary for formation of triglycerides. Nevertheless, with the volume requirements for a fuel source, the costs associated with the inputs are high.
In light of the above, it is an object of the present invention to provide a system and method for processing oil from algae which reduces input costs. For this purpose, a number of systems have been developed, such as those disclosed in co-pending U.S. patent application Ser. No. 11/549,532 for an invention entitled “Photosynthetic Oil Production in a Two-Stage Reactor,” co-pending U.S. patent application Ser. No. 11/549,541 for an invention entitled “Photosynthetic Carbon Dioxide Sequestration and Pollution Abatement” and co-pending U.S. patent application Ser. No. 11/549,552 for an invention entitled “High Photoefficiency Microalgae Bioreactors,” which are filed concurrently herewith and assigned to the same assignee as the present invention, and are hereby incorporated by reference. Another object of the present invention is to provide a recycling system for feeding oil harvesting byproducts back to the conduit where high oil content algae is grown. Still another object of the present invention is to provide a system for supplying nutrients to algae cells in the form of processed algae cell matter. Another object of the present invention is to provide a system for recycling the glycerin byproduct from the creation of biofuel as a source of carbon to foster further oil production in algae cells. Another object of the present invention is to provide a system for processing oil from algae that defines a flow path for continuous movement of the algae and its processed derivatives. Yet another object of the present invention is to provide a system and method for processing algae with high oil content that is simple to implement, easy to use, and comparatively cost effective.